Feeding means for underfeed stokers



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Inventov Fovvest L,Hit,chcoch u; I ma mi@ Attovnegs Patented Mar. 17, 1936 UNITED PATNT GFFHE FEEDING MEANS FOR UNDERFEED STOKERS Forrest L. Hitchcock, Indianapolis, Ind., assignor to FurnaSlave, Inc., Indianapolis, Ind.

Application August 16, 1934, Serial No. 740,129

Claims. (Cl. 198-221) This invention relates to the art of stokers Fig. 2, a vertical transverse section on the line and particularly to means for feeding solid fuel 2 2 in Fig. 1; into a combustion zone. A primary object of Fig. 3, a vertical transverse section on the line my invention is to provide a feeding means which 33 in Fig. 1;

- 5 will first of all feed fuel into the combustion Fig. 4, a top plan view with fragments of the 5 zone freely without danger of becoming clogged enclosing walls broken away to disclose interior or stopped by the fuel itself. The structure hereparts;

in shown and described is particularly adapted Fig. 5, a vertical transverse section on the line to feed fuel ranging in size from the commer- 5-5 in Fig. 4, illustrating a modified form of I1() cially termed pea size to the nut size. It is a ash conveyor; `10

further primary object of my invention to pro- Fig. 6, a central vertical longitudinal section vide a feeding mech-anism which will feed such through a feeding mechanism in modified form;

type of fuel with the minimum noise so that, in Fig. 7, a transverse central section through the the space to be heated, no noise will be percepmodified structure, and v tible, a slight noise, if any, arising by the passage Fig. 8, a transverse vertical section on the line 15 of the fuel through the mechanism being blocked 8 8 in Fig. 6.

off or insulated from the member into which the Like characters of reference indicate like parts fuel is fed for combustion. throughout the several views in the drawings.

A further primary object of my invention is I provide a main housing I0 which has a top V2O to provide a fuel feeding mechanism wherein opening I I into which fuel may be dropped. This 20 the fuel is not compacted within a tube but housing I0 is principally rectangular in vertical is moved along therethrough in relatively small cross section and is provided with an up-turned quantities so that the tube is not completely lled L I2 at the discharge end which has a circular at any time. A still further important object of cross section. There is an olf-set between the ,'25 the invention is to provide means for elevating juncture of the L I2 with the housing I0 as in- 25 the fuel from the conveying member into the dicated in Fig. 3 and the under side of the L I2 combustion zone in such a manner that there is is continued back under the housing I0 for a no tendency for the fuel to become clogged or Short distance to provide a base on which a head packed together when it is turned from the hori- I3 may slide. zontal direction to the vertical direction of travel. This head I3 is curved on its under side to 30 There is further included in my invention the conform to the curvature of the fioor of the L feature of employing a single unit to feed coal and is provided with a longitudinal slot to reinto and to convey ashes out of the unit within ceive therein the guide I4 which is fixed on the which the fuel is to be consumed all in a manoor of the L I2 to prevent circumferential travel 35 ner tending to utilize the minimum power and of the head I3 around the oor. 'The guide I4 35 vto operate with the minimum noise, but moreserves a further purpose in that its forward end over to so coordinate the ash removal with the serves as a stop against which fuel may rest as fuel feeding as to provide for the ashes being Will be further described hereinbelow. removed as accumulated without having to drive On the upper side of the head I3 and spaced 40 the mechanism at an excessive speed and withrearwardly from the forward end thereof is a 40 out having to employ a variable mechanism in floor I5 which ts slidably between the side walls relation to the fuel feeding mechanism. of the housing IIJ and extends rearwardly under Another feature of my invention resides in and beyond the opening II. The front end of the removal of the ashes from the unit in which the floor I5 is secured to the head I3 while the p the fuel is burned and conducting such ashes to rear end of the floor rests upon a transversely 45 a desired depository either sunk below the floor disposed plate I6 so that the floor is supported at level or placed thereabove. each end thereof to be substantially horizontal. These and other objects and advantages of the A step plate II is secured to the upper side of the invention will become apparent to those skilled in floor I5 at the rear end thereof, Fig. l, to extend the art in the following description of the invenforwardly under the opening I I in the housing I0. 50

` tion as illustrated by the accompanying drawings, A connecting rod I8 pivotally interconnects with in which the head I3 and extends rearwardly under the Fig. 1 is a central, longitudinal, vertical secfloor I5 into a power transmission box I 9 which tion through a structure embodying my invenis operated by a motor 20 to give suitable horizon- 55 tion; tal reciprocatory motion to the rod I8. The ex- 55 act details of the power transmission included in the box I9 are not here shown since they do not specifically enter into my invention.

The vertical walls of the housing Ill are provided with inwardly extending portions 2l and 22 the upper edges of which are stepped downwardly 'from the rear to the forward end of the housing to provide a series of shoulders 23 at decreasing elevations as the foiward end` of the housing is approached. The forward end of the head I3 is sloped upwardly and rearwardly and likewise the forward end of the guide I 4 is sloped upwardly and rearwardly.

The. L I2 has an increasing cross sectional diameter as it leaves the end of the housing I0 and turns around upwardly. Preferably the upward extension of the L is broken to have a separate pipe 24 fixed theretoand extending on upwardly into the desired combustion zone. This separate extension 22 is provided so that it may be connected to the discharge end of the L in a manner permitting some means of insulation to be incorporated therebetween so as to prevent transmission of sound from the L to the member 24 thereabove. In the particular form herein shown, this insulating means comprises a gasket 25 placed between the member 24 and the L I2, insulating thimbles 26 placed around the bolts 2l which pass through the flanges of the two members and I2 and insulating washers between the head and nut of each bolt to bear against the flanges of those members.

Below the housing Il and extending somewhat outwardly from each side thereof are disposed two ash conveying screws 28 and 23 supported to be revolved about their longitudinal axes. rI'he forward ends of these screws extend out along the side of the L I2 in the open while the rear and major portions thereof extend back within housings 3E and 3| extending outwardly from the base of the housing I5 and around and under the screws. A shaft 32 extending from the transmission box IS carries a sprocket 33 thereon around which a conveyor chain Sli is wrapped to extend downwardly and around sprockets on each of the screws 2B and 29 and thence back up to the sprocket 33 again. By means of this chain 34, the two screws are driven, and also the ashes being carried back by the screws toward the chain are scraped along the floor 35 to the elevator chain 3l, Fig. 5. When the ashes are to be placed in a receptacle sunk in the floor, the ashes will be discharged through an opening 36 directly from the screws into the receptacle which may be placed thereunder and the scraper blades on the chain 34 are then omitted.

In practice, the forward end of the structure above described is inserted within the furnace or unit to which fuel is to be fed to have the L I2 and the forward portion of the housing IIl at least back to that part where the screws 28 and 29 are covered over all within the ash pit or below the grates of the furnace or unit. Now as fuel is fed into the opening II, it drops downwardly to strike the plate Il and also the floor I5. Since the floor 5 and its plate Il' fit with a rather close fit between the lower ends of the sides of the housing it, the fuel will be retained on the floor and the plate. The oor I5 is given a fore and aft reciprocatory motion through the rod I8 so that as the floor I5 moves forwardly, fuel will be carried along therewith on the forward travel of the oor and will then tend to remain in that forward position by reason of friction on the side walls or rather the extending portions 2| and 22 thereon and further by reason of the fuel engaging against the shoulders 23 upon the initial return movement of the floor I5. 'Ihus the floor I5 and step plate I 'I may return rearwardly and then again upon the forward stroke, carry the fuel forwardly again. The fuel will drop down in front of the head I3 upon the return stroke. The succeeding feeds of fuel are facilitated by forward pressure of the step plate I'I thereagainst. While this plate I I tends to push the fuel forwardly the floor I5 being perfectly smooth over its major length will slip readily out from under the fuel so that additional fuel may be fed in front of the step plate Il and be carried forwardly again on the next forward stroke. Simultaneously with this conveying of the fuel forwardly through the housing IIJ, the forward end of the head I3 is intermittently pushing the fuel up around the L I2 until the L is completely filled so as to provide a foundation to support a column of fuel being urged up through the extension 24. The top level of the fuel within the housing I0 will rarely, if ever, be above the rear shoulder 23 so that a clearance is left between the upper side of the fuel and the top of the housing Ill. While it was stated above that the head I3 intermittently pushed the fuel ahead to fill the L I2, that L is not completely lled and the fuel therein is built up to have the rear part thereof follow some such contour as indicated by the dash lines, Fig. 1.

It is to be particularly noted that the head I3 pushes forwardly on the under side of the fuel only. The length of the stroke of the head I3 is such that its forward end will just come about even with the front end of the guide I4. Now as the head I3 returns rearwardly, the fuel within the L is prevented from falling back down principally by the fuel bank thereunder aided by the forward end of the guide I4 serving as a stop to prevent the fuel from sliding rearwardly. By reason of the fact that the fuel is fed into the L i2 in the manner stated by the head I3 and also by reason of the fact that the L I2 is tapered, the fuel is fed around the bend without tending to become clogged, or impacted therein. The speed at which the floor I5 is reciprocated determines the rate of feed of fuel through the L I2.

Ashes are permitted to drop down freely around the L I2 and the forward end of the housing Ill to build up therearound sufficiently to permit the screws 28 and 29 to be fed by the ashes sliding theretoward so that as the screws revolve, they will feed the ashes back along under the housing I Il through the laterally extending housings 30 and 3| where the ashes may be eventually dropped through the opening 36 as above indicated. The shape of the screws 28 and 29 and their rate of travel are so predetermined that the ashes as formed will be withdrawn at a sufficient rate of speed to keep the ashes removed without building up unduly around the L I2 and housing I0. In other words, these elements are so designed as to be operative in accordance with the feed of fuel by the floor I5.

Where it is not desired to drop the ashes through an opening into a receptacle below the feeding mechanism, some elevating device may be employed as indicated in Fig. 5 where the conveyor chain 31 may carry the ashes around up a conveyor floor 38 to elevate them sufcently high to permit them to drop out of the elevator at some upper elevation over a receptacle. I It is preferred at all times to arrange the ash conveyor so that it may discharge directly over a receptacle which may be enclosed, particularly dust tight, so that as the ashes drop therein, the dust will be confined within the receptacle and the elevator, the elevator being suitably connected with the receptacle closure so as to retain the dust and prevent its escape into the room.

Where a smaller unit is desired, a modified form of the structure may be employed such as is shown in Figs. 6, 7 and 8. In this modified form, a housing 40 is employed which has a circular cross section. Fuel is fed into the housing 40 through the entry 4l where it may drop in front of a plunger 42. `This plunger 42 reciprocates rearwardly and forwardly but never entirely across the entry 4l, the forward limit of travel being approximately that position as indicated in Fig. 6. The upper forward face of the plunger is preferably sloped rearwardly. A pair of guides 43 and 44 are xed within the housing 40 to extend longitudinally therealong and toward the bottom thereof and the plunger 42 is notched out to fit over these guides so that the plunger 42 may be reciprocated freely thereover and be prevented from circumferentially revolving within the housing 40.

These guides 43 and 44 extend beyond the forward limit of travel of the plunger 42 and serve as fuel stops as will be hereinafter more fully indicated. Fixed to opposite sides of the plunger 42 are fingers 45 and 46 which extend horizontally forwardly throughout substantially the entire length of the housing 40 and tern minate with beveled ends. Both of these fingers 45 and 46 are provided with shoulders 41 and 48 respectively about half way of their length ahead of the plunger 42, these shoulders being formed as herein shown by placing bars 49 and 50l on the inner faces of the fingers 45 and 46 to have the forward ends of such bars forming the shoulders 41 and 48. These shoulders are left square and not beveled. Also a fin-ger l is fixed to the under side of the plunger 42 and extends forwardly along the floor or bottom of the housing 40 to terminate with a beveled end in the plane of the ends of the side fingers 45 and 46. This finger 5| is also provided with a shoulder 52 substantially at its midway ahead of the plunger 42, the shoulder 52 being formed by the end of a bar 53 which is xed to the finger 5I to extend rearwardly back to the plunger 42.

The forward end of the housing 4B is turned around from the horizontal to extend upwardly and has an extended feed pipe 54 fixed thereto, preferably in an insulated manner such as above described.

In this modified form, being a smaller unit, but one ash conveying screw 55 is employed and this screw is centrally mounted under the housing 40 to be carried by a bearing at its forward end and extending back through a tubular housing 56 suspended under the housing 46. A conveyor chain 51 is driven by a sprocket 6I o-n the screw 55 to extend to any desired position so as to discharge the ashes brought to the chain by the screw 55. When the ashes `are to be dropped through an opening 62 in the bottom of the housing 56, then the sprocket 6l and chain 51 are dispensed with.

In operation, the fuel is dumped through the entry 4I into the housing 4B at such rate that the entry is not completely filled up and the plunger 42 through its repeated reciprocations may carry the fuel forwardly within the housing 40 without completely filling that housing. As

vate the fuel into the extension 24.

the plunger 42 moves forwardly against the fuel,

the fingers 45, 46 and 5l move forwardly also and by reason of their forward ends and the shoulders 41, 48 and 52 carried thereby push the fuel forwardly step by step and push it around v5 the L at the end of the housing 40 so as to ele- As the plunger 42 withdraws or moves rearwardly, the fingers may be stripped from the fuel which is prevented from following by reason of the forward blunt ends of the guides 43 and 44 being present and by reason of the fuel resting on the wall of the housing 40. The plunger 42 is reciprocated by a connecting rod 53 which is driven through a suitable transmission device within the-15 housing 59 by a motor 60.

Bo-th forms of the feeding mechanism above described are particularly well adapted for feed- Iing coke.

The feeding mechanism is also particularly adapted to underfeed grates of the type indicated in my copending application for U. S. Letters Patent Serial No. 725,557, filed May 14, 1934.

While I have herein shown and described my invention in the best forms as now known to me,- itis obvious that structural variations may be made Without departing from the spirit of the invention and I, therefore, do not desire to be limited to the precise forms as herein shown and described nor any more than may be required` by the following claims.

I claim:

1. In a solid fuel stoker feeding device, a fuel directing housing, an L on the discharge end of the housing, a reciprocable member within and` on the underside of the housing for pushing fuel along in the housing and into said L, saidmember being formed to move a volume of fuel less in height than that of the interior of the housing so that a free space is maintained in the hous-Y ing above the fuel therein, and fixed stops on the interior of the housing tending to strip said member of fuel upon its return stroke.

2. In a solid fuel stoker feeding device, a fuel directing housing, an L on the discharge end ofthe housing, a reciprocable member within and on the underside of the housing for pushing fuel along in the housing and into said L, said member being formed to move a volume of fuel less in height than that of the interior of the hous-.r ing so that a free space is maintained in the housing above the fuel therein, and fixed stops on the interior of the housing tending to strip said member of fuel upon its return stroke, said member comprising an elongated finger, and a headff5 carrying the finger, said housing having an opening through which fuel enters, and said head being placed to move over at least a part of said opening to push fuel away therefrom.

3. In a solid fuel Stoker feeding device, a fuelgo directing housing, an L on the discharge end of the housing, a reciprocable member within and on the underside of the housing for pushing fuel along in the housing and into said L, said member being formed to move a volume of fuel 65 less in height than that of the interior of the housing so that a free space is maintained in the housing above the fuel therein, and fixed stops on the interior of the housing tending to strip said member of fuel upon its return stroke, said member comprising an elongated finger, and a head carrying the fingen, said housing having an opening through which fuel enters, and said head being placed to move over at least a part of said opening to push fuel away therefrom, and additional fingers carried by said head extending Within and along the sides of said housing.

4. In a solid fuel stoker feeding device, a fuel directing housing, an L on the discharge end of the housing, a reciprocable member Within and on the underside of the housing for pushing fuel along in the housing and into said L, said member being formed to move a volume of fuel less in height than that of the interior of the housing so that a free space is maintained in the housing above the fuel therein, and fixed stops ron the interior of the housing tending to strip said member of fuel along its return stroke, said vmember comprising the floor of the housing, a head fixed on the discharge. Vend of the floor spacing the floor above the floor of the L and having its forward face below the floor, and a stop substantially at the juncture of the end ofi thecurved floor of the L and a horizontal apron extending rearwardly therefrom, said stop being forwardV of the head when it is back of its forward limit of travel. j

5. In a solid fuel stoker feeding device, a fuel directing housing, an L on the discharge end of the housing, a reciprocable member within and on the underside ofthe housing for pushing fuel along in the housing and into said L, said member being formed to move a volume of fuel less in height than that of the interior of the housing so that a free space is maintained in the housing above the fuel therein, and fixed stops `on the interior of the housing tending toy strip said member of fuel along its return stroke, said member comprising Vthe floor of thehousing, a head xed on the discharge end of the floor spacing the oor above the floor of the L and having its forward face below` the floor, and a stop substantially at the juncture of the end of the curved floor of the L and a horizontal apron extending rearwardly therefrom, said stop being forward of the head when it is back of its forward limit of travel, and a series of stepped inwardly projecting shoulders on the side walls of the housing above said floor.

6. In a solid fuel stoker feeding device, a fuel directing housing, anL on the discharge end of the housing, a reciprocable member within and on the underside of the housing for pushing fuel along in the housing and into said L, said member being formed to move a volume of fuel less in height than that of the interiorof the housing so that a' free space is maintained in the housing above the fuel therein, and, xed stopsion the interior ofjthe housing ptending to strip. said member of fuel alongits return stroke, said member comprising the floor of the housing. ahead xed on the discharge end'of the floor spacing the floor above the floor of the L and having its forward face below the oor, and a. stop-substantially at the juncture of the end of thecurved rearwardly therefrom, said stop being forward of the head when it is back of its forward limit of travel, and a step on the rear upperside of the floor, Ysaid step being located under a fuel receiving opening in said housing, whereby said step upon reciprocating travel of the floor will hold the fuel stationary on the oor in the forward travel but may slip out thereunder upon rearward travel.

7. In a solidfuel stoker feeding device, a fuel directing housing, an L ontne discharge end of the housing, a reciprocable member within and on the underside of the housing for pushing fuel along in the housing and into said L, said member being formed to` move a Volume of fuel less in height than that ofthe interior of the housing so that-a free space is maintained in the housing above thefuel therein, and fixed stops on the interior. of the housing tending to strip said member of fuel upon its return stroke, a fuel conductingpipe supportedby said L, and sound insulating means interposed between the pipe and L and said L flaring from said housing whereby in conjunction with free movement of fuel through the L and said insulation, crushing and grinding sound of the moving fuel is not transmitted to said pipe. y

8. In a solid fuel Stoker feeding means, a fuel directing'housing, reciprocatinglmeans for carrying. fuel alongthe bottom of the housing, and fuel return stop means comprising stationary shoulders on the housing ahead ofand at the sides of said reciprocating means holding fuel in a forward position during return'travel of said reciprocating means.v

9. In a solid fuel stoker feeding means, a fuel directing housing, reciprocating means' for carrying fuel alongthebottom of the housing, and fuel return stop mea-ns comprising stationary shoulders on Vthehousing ahead of andiat the sides of said reciprocating means holding fuel in a forward position during return travel of said reciprocating means, and an upturned L on the discharge end of the homing, said reciprocating means being formed tofeed fuel into the L along and around the underside thereof.

10. In a'solid fuel sto-ker feeding means, a fuel directingihousing, reciprocating means for carrying fuel along the .bottom of the housing, and fuel return stop means comprising stationary shoulders on the .housing ahead of and at Ythe'sides of j said reciprocating means vholding fuelin a for- ;ward position during return travel 'of said re- -`cipro'cating means, andan upturned L on the discharge end of the housing, Said-reciprocating meansbeing formed to feed fuel into the L along 'and around the underside thereof, said L having a cross-sectionalarea at its juncture with the housing less than .that ofY the housing, said area Y increasing aroundv theV L. floor of the L anda horizontal apron extending l FORRES' L.l HITCHCOCK. 

